Difference between Carapace and Plastron


It is the dorsal part of the exoskeleton seen in crustaceans and arachnids and also in some arthropods. In crustaceans, it is found as a covering over their fused thorax and head region. The forward extension of this covering over the eyes is called the rostrum. The degree of calcification in carapace varies with the crustacean species. In arachnids, it is seen as a single plate carrying the ocularium, eyes, and ozopores. The carapace is also seen in tortoises and turtles.


In vertebrates, like tortoises and turtles, the dorsal side is covered by the carapace, and the ventral side is covered by plastron. A typical plastron is made of nine bones. In some species of turtles, the males show concave plastron and the females show convex structure. This helps them during the copulation. Also, sometimes, the females have light coloured plastron compared to the males. These features help to identify the sex of the Testudines.

Difference between Carapace and Plastron



Carapace is a protective exoskeleton on the dorsal side.

Plastron is a protective shield that is typically on the ventral side.

It is a convex structure.

It can be a flat, convex or concave structure.

Frequently Asked Questions

Frequently Asked Questions on Difference between Carapace and Plastron


What are the structures in a typical vertebrate carapace?

In vertebrates like turtles and tortoises, the carapace is a protective shell covering most vital organs. This shell constitutes the rib cage of the animal and the scutes. Scutes are keratinised structures seen on the carapace.


What is an osteoderm?

Oesteoderm is a dermal bony deposition that is viewed as scales or plates in many reptiles, a few anurans and mammals. For example, the scaly coverings on lizards, crocodiles, armadillos, etc.


What is a dermal bone?

It is a bony structure that forms a major component of the vertebral skeletal system. This dermal bone includes the jaws, skull, fin spines and shell. It usually arises within the dermis. The outer part of this bone contains the osteoblast depositions.

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